1. Field of the Invention
The present invention relates to a fan motor, mounted, for example, to a thin electronic appliance such as a notebook type personal computer, including fan blades extending radially from around a perimeter of a rotor.
2. Description of Related Prior Art
In recent years, increase in processing speed of electronic components (e.g. MPU) for processing various data such as letters, sounds and/or images as well as further multi-functionality thereof has been strived for. Those electronic appliances tend to emit more heat as the degree of circuit integration and the performance of electronic components enhance.
On the other hand, further small-sizing and thinning have been required in a field of thin electronic appliances such as notebook computers, and thus it has been a crucial issue how the heat from electronic components mounted on a printed board is effectively cooled within such a limited space as the inside of a thin electronic appliance. Thus, a cooling fan with fan blades provided radially from around a rotor is installed to the inside of a thin electronic appliance in order to control heat of electronic components such as MPU.
Conventional centrifugal fan motors, as disclosed in Japanese Un-Examined Patent Publication No. 2004-140061, comprises a casing serving as a base for installing a fan body thereto and a cover for covering an upper surface of a frame, thus defining an outer contour having an air sending passage formed thereinside. The casing includes a rotor with fan blades arranged radially with respect to a rotational axis thereof and a motor serving as a drive force for imparting rotary drive to the rotor, thus providing a fan assembly of a double-sided-air-intake type.
Referring to FIG. 6 showing a more specific structure of the conventional fan motor, the outer contour of a flat fan motor 1 is composed of a casing 2 and a cover 3, while a fan assembly 7 comprising: a cup-shaped rotor 4; a plurality of fan blades extending fan around a perimeter of the rotor 4; and a motor 6 for imparting rotary drive force to the rotor 4 is accommodated into the outer contour of the fan motor 1. Intake holes 8, 9 for sending air to the fan assembly 7 are provided in the casing 2 and the cover 8, respectively, said intake holes 8, 9 being located on opposite ends along a rotational axis 4A of the rotor 4. A discharge hole 10 for discharging air to the outside is provided in the direction orthogonal to the respective intake holes 8 and 9.
When the fan blades 5 are rotated together with the rotor 4 by energizing the motor 6, air F is drawn in from the two intake holes 8, 9 provided on top and bottom sides of the fan assembly 7. The air thus drawn in is fed out toward the rotation direction of the fan blades 5 so that it is discharged toward the outside of the thin electronic appliance from the discharge hole 10 provided on one side of the fan motor 1 through the fan motor 1.
Referring now to FIGS. 7(A) and 7(B) each showing a section of the conventional fan blade 5 of FIG. 6, FIG. 7(A) shows a section of an air intake part 21 where air F is drawn in, while FIG. 7(B) shows a section of a distal part 22 located more distantly from the rotational axis 4A in the center of the rotor 4 than the air intake part 21. Numerals 23A and 24A designate a front surface of the air intake part 21 facing toward the rotating direction of the fan blade 5 and a rear surface thereof, respectively, while numerals 28B and 24B designate a front surface of the distal part 22 facing toward the rotating direction of the fan blade 5 and a rear surface thereof, respectively.
FIG. 8 illustrates the airflow F at the rotor 4 side (i.e., the proximal side) of the fan blade 5, which is in other words at the air intake part 21 side, where the front surface 23A facing toward the rotating direction of the fan blade 5 has the same contour as the front surface 23B at the perimetric (i.e., distal) side of the fan blade 5, which is in other words at the distal part 22 side, and thus it is arranged perpendicularly to an intake face for introducing air F from the intake holes 8 and 9. It is to be noted that the above-mentioned configuration of the front surface 23A only functions to impel the air F drawn into the air intake part 21 toward the perimetric direction, and makes no contribution to the intake of air toward the fan blade 5, which has caused dissatisfaction to users.